The instant invention relates to data input devices used by people who are physically handicapped in the use of their arms and fingers. The conventional means of data entry devices used by individuals who are physically handicapped in the use of their arms and fingers is to employ special keyboards, mouth sticks or head pointers. Special keyboards, such as those equipped with unusually large key switches or protective masks surrounding the key switches, depend upon the limited usage of an arm or finger muscles and most oftentimes cannot be successfully used by those who are totally paralyzed in those areas. Mouth sticks and head pointers which are designed to either close key switches or to direct a beam of light to electronic sensors are relatively slow and are not suitable to be used by those who are disabled with head and neck impairments.
In prior art devices, characters visible on a display panel are sequentially accentuated by means of illumination of miniature lights. (The process of sequentially accentuating the display characters is referred to herein as "scanning"). When a user selects a character, he waits until that character is accentuated, or highlighted, and at the precise moment that the selected character is accentuated, the user effects a switch closure by means of a pressure sensitive switch or other similar device. If the user wishes to "scan" the characters on the visible display board in front of him, he typically is able to select, from one or two constant speeds, a scanning speed by means of switch closures. However, once the scanning speed is selected, that speed remains in effect until a new scanning speed is selected via a different combination of switch closures. The above-mentioned prior art devices therefore have deficiencies in controlling the actual input of selected characters and in varying the speed by which characters are scanned.